No. I made the mistake of wearing a 50/50% wool cotton mix over my polypro base and believe me it sucked. When we took a lunch break I was shivering my ass off.

I'll take a different view, and say yes, you can. Here is why. If you sweat, and the first thing it comes in contact with is cotton, your in trouble. However, if goes into a wicking fabric first, it will help disipate the moister a good deal BEFORE it gets to a secondary cotton layer. Yeah, it wouldnt be as good as if you had two wicking type shirts on, but I've never had any major issue with like a UA compression shirt under a cotton t-shirt before. *shrugs*

I'll take a different view, and say yes, you can. Here is why. If you sweat, and the first thing it comes in contact with is cotton, your in trouble. However, if goes into a wicking fabric first, it will help disipate the moister a good deal BEFORE it gets to a secondary cotton layer. Yeah, it wouldnt be as good as if you had two wicking type shirts on, but I've never had any major issue with like a UA compression shirt under a cotton t-shirt before. *shrugs*

Well it probably depends on how much you sweat, etc., but once the second layer gets saturated, the base layer won't be able to do its job. No matter how good it is at wicking, it can't make the second layer wick, so the moisture is stuck. I only noticed the effect when I took breaks and was cooling down. It also didn't seem to bother me when I was younger. If it works for you, go for it. You can save some money on the second layer.

Well it probably depends on how much you sweat, etc., but once the second layer gets saturated, the base layer won't be able to do its job. No matter how good it is at wicking, it can't make the second layer wick, so the moisture is stuck. I only noticed the effect when I took breaks and was cooling down. It also didn't seem to bother me when I was younger. If it works for you, go for it. You can save some money on the second layer.

I learned a good trick backpacking during the summer, if you wear a cotton shirt over a wicking layer like capilene, carry an extra t-shirt. I usually go with a Patagonia zip capilene under a t-shirt, but always carry spare.